1. Field of the Invention
The present invention relates to a driving force transmission mechanism which comprises a first member that is moved by a driving force from a driving source, a second member that is moved by coming in contact with the first member when the first member is being moved, and a cover member that is arranged between the first member and the second member.
2. Description of the Related Art
An endoscope apparatus which comprises an endoscope comprising an insertion section, and an insertion assisting tool attached to the outer periphery of the insertion section to assist its insertion is known. For example, International Publication No. 2013/038720 discloses an endoscope apparatus comprising an endoscope comprising an insertion section extending in a longitudinal axis direction, a drive ring attached to the insertion section, and a tubular drive tube attached to the outer periphery of the drive ring. The drive ring and the drive tube are attached so as to be coaxial with the insertion section of the endoscope.
In the endoscope apparatus, a flexible drive shaft is arranged on the insertion section of the endoscope. The drive ring comprises a stator, a rotor which is rotatable around the stator and is detachably connected to the drive tube, a rotation gear which is configured to transmit rotary motion from the drive shaft to the rotor in order to rotate the drive tube, and a cylindrical cover member which covers the outer periphery of the stator.
On the outer periphery of the rotation gear is provided a plurality of transfer rollers (internal rollers), and on the inner surface of the rotor is provided a plurality of housing rollers (external rollers). The cover member is fixed on the surface of the stator and is arranged between the transportation rollers and the housing rollers. Furthermore, on the outer periphery of the drive tube is provided a spirally formed fin.
When observing a serpentine tubular organ, etc. such as a large intestine or a small intestine using the above-mentioned endoscope apparatus, the drive tube is rotated in its longitudinal axis direction by rotating the transfer rollers and the housing rollers by the driving force transmitted from the drive shaft and the rotation gear. The insertion section advances while the spiral fin of the rotating drive tube pushes the wall, such as the intestinal wall, to which it abuts. In this manner, the insertion section is assisted to be inserted into the deep site of the organ.